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Situation assessment is crucial for intelligent vehicles, enabling detection of potential risks to dynamic and complex traffic environments. In this paper, we propose a unified framework that tackles the coupling relationships between traffic participants and quantifies the possible range of vehicle trajectory generation and the expected losses caused by risk source attributes in the driving process. We first apply the state space trajectory planning scheme based on a sampling algorithm to generate the path candidates; each feasible path is designed through a parametric cubic spline. Then, to evaluate the risk range in the driving process, we quantify the interaction of traffic participants, and employ the principle of least action to calculate the cost of each feasible path when achieving the destination. The probability distribution map, namely the possible range of driving trajectories, can be obtained based on the path cost. Furthermore, the vehicle-to-vehicle interaction is calculated based on the equivalent force, which estimates the expected accident losses. Finally, the vehicle trajectory prediction and the expected loss are combined to output the probabilistic situation assessment of intelligent vehicles. The algorithm is implemented in different scenarios and applied to the trajectory planning process. Results demonstrate that, compared with the classical situation assessment metric, the developed method can determine and accurately identify the influence range of driving risk in real-time, predict a dangerous situation earlier, and ensure the vehicle avoids obstacles in advance.

Two-dimensional (2D) transition metal chalcogenides (TMCs) become more attractive upon addition of a third element owing to their unique structure and remarkable physical and chemical properties, which endow these materials with considerable potential for applications in nanoscale devices. In this work, a RexNb(1-x)S2-based saturable absorber (SA) device for ultrafast photonics applications is studied. The device is assembled by placing RexNb(1-x)S2 nanosheets with a thickness of 1-3 nm onto a microfiber to increase their compatibility with an all-fiber laser cavity. The prepared RexNb(1-x)S2-based device exhibits a modulation depth of 24.3%, a saturation intensity of 10.1 MW/cm2, and a nonsaturable loss of 28.5%. Furthermore, the RexNb(1-x)S2-based device is used to generate ultrashort pulses in an erbium-doped fiber (EDF) laser cavity. At a pump power of 260 mW, the EDF laser operates in a conventional soliton mode-locked region. The pulse width is 285 fs, and the repetition frequency is 61.993 MHz. In particular, the bound-state soliton mode-locking operation is successfully obtained in a pump power range of 300-900 mW. The bound-state pulses are formed by doubling identical solitons with a temporal interval of 0.8 ps. The output power is as high as 47.9 mW, and the repetition frequency is 123.61 MHz. These results indicate that the proposed RexNb(1-x)S2-based SAs have comparable properties to currently used 2D SAs and provide a basis for their application in the field of ultrafast photonics.

The high cost, scarcity, and poor stability of precious-metal-based catalysts have hindered their extensive application in energy conversion and storage. This stimulates the search for earth-abundant alternatives to replace noble metal electrocatalysts. Hence, in this study, we investigate a novel and low-cost bifunctional electrocatalyst consisting of ZnCoMnO4 anchored on nitrogen-doped graphene oxide (ZnCoMnO4/N-rGO). Benefiting from the strong Co-N interaction in ZnCoMnO4 and the coupled conductive N-rGO, the catalysts exhibit high electrocatalytic activity. Moreover, density functional theory calculations support the dominant role of the strong Co-N electronic interaction, which leads to ZnCoMnO4/N-rGO having more favorable binding energies with O2 and H2O, resulting in fast reaction kinetics. The obtained ZnCoMnO4/N-rGO electrocatalyst exhibits superb bifunctional activity, with a half-wave potential of 0.83 V for the oxygen reduction reaction and a low onset potential of 1.57 V for the oxygen evolution reaction in 0.1 M KOH solution. Furthermore, a Zn-air battery driven by the ZnCoMnO4/N-rGO catalyst shows remarkable discharge/charge performance, with a power density of 138.52 mW cm−2 and long-term cycling stability for 48 h. This work provides a promising multifunctional electrocatalyst based on non-noble metals for the storage and conversion of renewable energy.

The photocatalytic water splitting has a stupendous role to generate renewable hydrogen. However, the overall water splitting reaction is limited by the sluggish oxidation step. Bismuth vanadate (BiVO4) has been identified as one of the most promising n-type semiconductors for photocatalytic water oxidation due to its small energy gap and favorable band alignment. Thus, it is necessary to summarize the recent progress done on BiVO4 for the guidance of future research. In this review, we have discussed recent strategies that have been adopted to boost its photoconversion efficiency at three different levels: (1) facet control, (2) morphological control and, (3) interfacial control. The roles of high indexed facets, anisotropic morphologies, and mediator-based Z schemes are comprehensively discussed and the emphasis is given to find the suitable structural, morphological, and interfacial combination of BiVO4 for efficient water oxidation.

To better promote the application of polymeric mixed micelles (PMMs), a coarse-grained molecular dynamics simulation (CGMD) has been employed to investigate the factors controlling the spatial distribution within the PMMs and predict their drug-loading properties, meanwhile, combined with experimental methods to validate and examine it. In this study, the snapshots obtained from CGMD and the results of proton nuclear magnetic resonance (1H NMR) and transmission electron microscopy (TEM) provide new insights into the distribution principle that the spatial distribution depends on the hydrophobic compatibility of drugs with the regions within PMMs. Docetaxel (DTX) is located within the interior or near the core-corona interface of the HS15 hydrophobic core inside FS/PMMs (PMMs fabricated from a nonionic triblock copolymer (F127)) and a nonionic surfactant (HS15), and therefore, the system with a high HS15 ratio, such as system I, is more suitable for loading DTX. In contrast, the more water-soluble puerarin (PUE) is more likely to be solubilized in the "secondary hydrophobic area," mainly formed by the hydrophobic part of F127 within FS/PMMs. However, when the initial feeding concentration of the drug is increased or the FS mixing ratios are changed, an inappropriate distribution would occur and hence influence the drug-loading stability. Also, this impact was further elucidated by the calculated parameters (solvent-accessible surface area (SASA), the radius of gyration (Rg), and energy landscape), and the analysis of the drug leakage, concluding that inappropriate distribution of the drug would lower the stability of the drug in the PMMs. These results combined together provide new insights into the distribution principle that the spatial distribution of drugs within PMMs depends on the hydrophobic compatibility of drugs with the regions formed by micellar materials. Additionally, in vitro drug release yielded a consistent picture with the above conclusions and provides evidence that both the location of the drug within the systems and the stability of the drug-loading system have a great influence on the drug release behavior. Accordingly, this work demonstrates that we can tune the drug-loading stability and drug release behavior via the drug-PMM interaction and drug location study, and CGMD technology would be a step forward in the search for suitable drug-delivery PMMs.

The corrosion behavior at open circuit potential (OCP) and discharge properties under applied anodic currents of two α-Mg based Mg-Li alloys, i.e., LAZ131 and LAZ531, with different microstructural features for primary Mg-air batteries are investigated. The results show that the grain boundaries contribute equally to the corrosion and discharge processes, which are attacked preferentially than the grain interiors and accelerate the dissolution processes of α-Mg based Mg-Li alloys. The (10−10)/(11–20) orientated grains are attacked preferentially than the (0002) orientated grains on the corrosion and discharge process. The increased corrosion rate and improved discharge properties are attributed to the refinement of grain size, decreased content of (0002) orientated grains and increased content of (10−10)/(11–20) orientated grains. Of those, the LAZ531 alloy possesses high and steady discharge voltage at small discharge current density for long time, with the values of 1.4801 V at 2.5 mA cm−2 and 1.3742 V at 10 mA cm−2.

Ternary transition metal chalcogenides (TTMDCs), a novel type of two-dimensional (2D) three-element materials, possess multiple physical and chemical properties and have promising potentials in basic physics and devices. Herein, the usage of WxNb(1−x)Se2 nanosheets as a rising ultrafast photonic device to generate high power mode-locked and Q-switched pulses in a fiber laser is demonstrated. The WxNb(1−x)Se2 nanosheets were successfully prepared by the liquid exfoliation method with thickness less than 3 nm. The nonlinear optical absorption of the WxNb(1−x)Se2-based device was investigated with the saturable intensity of 40.93 MW cm−2 and modulation depth of 5.43%. After integrating the WxNb(1−x)Se2-based device into an Er-doped fiber (EDF) laser cavity, mode-locking and Q-switching laser pulses were formed. In the mode-locked mechanism output, the pulse width is as narrow as 131 fs and the output power is 52.93 mW. In Q-switched operation, the shortest pulse duration is 1.47 μs with the largest pulse energy of 257 nJ. Compared to recent studies, our results showed some improvements. This study suggests that 2D TTMDC-based devices could be developed as efficient ultrafast photonics candidates and widely used in nonlinear optical applications.

The liquid crystalline and rheological properties of chitin whiskers (CHWs) are significant for their application in fabrication of highly ordered composite materials and optical components. The aim of this work was to elucidate the influence of chemical structure and chargeability (zeta potential, electropositivity, electronegativity or zwitterionic character) on the liquid crystalline and rheological properties of CHWs. Firstly, CHWs with different chemical structure, including positively charged whiskers (CHWs and CHWs-D/60 min) and negatively charged whiskers (mCHWs), were designed via acid hydrolysis, deacetylation, and maleation, respectively. Subsequently, the chargeability of the above whiskers was further regulated by protonation or deprotonation. The whisker aqueous suspensions with high zeta potential behaved as nematic liquid crystals or chiral nematic liquid crystals, whereas those with low zeta potential had no liquid crystal characteristics. The viscosity, G', and G" values of the CHWs and CHWs-D/60 min aqueous suspensions treated with protonation were lower than those of the corresponding whiskers treated with deprotonation. However, the mCHWs exhibited different changes in their rheological properties under protonation or deprotonation due to the electronegativity and zwitterionic characteristics. In addition, the effects of ionic strength and pH on the liquid crystalline and rheological properties of CHWs, CHWs-D/60 min, and mCHWs aqueous suspensions varied since the chemical structure and chargeability of whiskers differ.

Amorphous gallium tin oxide (GTO) thin films were prepared by a facile, and eco-friendly, aqueous solution process and their applications in thin-film transistors (TFTs) were investigated. The success of the aqueous route was realized by introducing tin fluoride (SnF2) instead of the traditional tin chloride (SnCl2) solute. The roles of adding Ga on the GTO’s microstructural, optical, chemical, and electrical performance were comprehensively studied. It was found that Ga can frustrate the crystallization while it augments the optical bandgap (Eg) value of pristine SnO2. More importantly, using Ga could effectively inhibit the formation of oxygen vacancies, thus greatly improving the electrical performance of the GTO TFTs. The amorphous GTO TFTs with a Ga content of 45% exhibited optimum performance, with a saturation mobility (μsat) of 4.26 cm2/V s, an on/off current ratio (Ion/Ioff) >107, and a decent bias stress durability.

IV–VI semiconductors have attracted widespread attention in basic research and practical applications, because of their electrical and optoelectronic properties comparable to graphene. Herein, an optical modulator based on SnSSe with strong nonlinearity is prepared by chemical vapor transfer method. The modulation depth of proposed SnSSe saturable absorber (SA) is up to 57.5%. By incorporating SnSSe SA into the laser, the Q-switched pulses as short as 547.8 ns are achieved at 1530.07 nm. As far as we know, this is the first successful application of SnSSe in Q-switched lasers. Our investigation not only prove the optical nonlinearity of SnSSe, but also reveal the potential of SnSSe SA in ultrafast photonics.

Transition metal dichalcogenides have been widely utilized as nonlinear optical materials for laser pulse generation applications. Herein, we study the nonlinear optical properties of a VS2-based optical device and its application as a new saturable absorber (SA) for high-power pulse generation. Few-layer VS2 nanosheets are deposited on the tapered region of a microfiber to form an SA device, which shows a modulation depth of 40.52%. After incorporating the microfiber-VS2 SA into an Er-doped fiber laser cavity, passively Q-switched pulse trains could be obtained with repetition rates varying from 95 to 233 kHz. Under the pump power of 890 mW, the largest output power and shortest pulse duration are measured to be 43 mW and 854 ns, respectively. The high signal-to-noise ratio of 60 dB confirms the excellent stability of the Q-switching state. To the best of our knolowdge, this is the first illustration of using VS2 as an SA. Our experimental results demonstrate that VS2 nanomaterials have a large potential for nonlinear optics applications.

In this study, pulsed laser deposition method (PLD) was employed to grow MgxZn1-xO films on quartz substrates. The optimal deposition temperature of 300 °C for MgxZn1-xO film was decided and Mg0.38Zn0.62O, Mg0.56Zn0.44O and Mg0.69Zn0.31O films were grown respectively using MgxZn1-xO targets with different Mg contents (x = 0.3, 0.5 and 0.7). As-deposited Mg0.38Zn0.62O film possessed the mixed-phase (hexagonal and cubic phase) structure, appropriate band gap of 4.68 eV and smaller surface roughness of 1.72 nm, and the solar-blind photodetector (PD) based on it was fabricated. The key features of our PD are the cutoff wavelength of 265 nm lying in solar-blind band, lower dark current (Idark) of 88 pA, higher peak responsivity of 0.10 A/W and bigger Ilight/Idark ratio of 1688, which provide the new idea for the application of solar-blind PDs based on MgxZn1-xO films.

Superelasticity associated with the martensitic transformation has found a broad range of engineering applications1,2. However, the intrinsic hysteresis3 and temperature sensitivity4 of the first-order phase transformation significantly hinder the usage of smart metallic components in many critical areas. Here, we report a large superelasticity up to 15.2% strain in [001]-oriented NiCoFeGa single crystals, exhibiting non-hysteretic mechanical responses, a small temperature dependence and high-energy-storage capability and cyclic stability over a wide temperature and composition range. In situ synchrotron X-ray diffraction measurements show that the superelasticity is correlated with a stress-induced continuous variation of lattice parameter accompanied by structural fluctuation. Neutron diffraction and electron microscopy observations reveal an unprecedented microstructure consisting of atomic-level entanglement of ordered and disordered crystal structures, which can be manipulated to tune the superelasticity. The discovery of the large elasticity related to the entangled structure paves the way for exploiting elastic strain engineering and development of related functional materials. NiCoFeGa single crystals exhibit large non-hysteretic superelasticity over broad temperature and composition ranges. It is attributed to the continuous phase transition with applied stress, which is related to the fluctuation of entangled ordered and disordered crystal structures.

Recently, metal surface plasma technology has been widely used to improve the quantum efficiency of optoelectronic devices, such as ZnO light-emitting diodes (LEDs). In this work, Ag films with the appropriate thickness were prepared by evaporation and annealed, and a layer of ZnCdO films with different Cd concentrations was grown on the Ag films by the pulsed laser deposition method. During this process, the changes in the Cd concentrations caused the near-band edge (NBE) emission of the ZnCdO films to be continuously adjusted in the ultraviolet to green wavelength range by controlling the oxygen pressure. The prepared Ag nanoparticles and ZnCdO composite films were used to study the metal localized surface plasmon (LSP) effect. The results show that the enhanced or reduced photoluminescence intensity of ZnCdO NBE depends on the probability of electrons transport to either the LSP level or the Fermi level of the metal. This discovery provides an important theoretical basis for the preparation of ZnCdO semiconductor LEDs in the future.

Tungsten oxide microflowers (WO3 MFs) were fabricated by a simple hydrothermal process through adjusting the pH of the solution by HCl. These MFs possess the outer diameters of about 2 μm and are composed of numerous nanoplates with the average pore size of 10.9 nm. Chemiresistive activity of as-fabricated WO3 MFs sensor was attempted towards oxidizing and reducing target gases, revealing a superior selectivity to NO2 with a maximum response of 22.95 (2 ppm NO2) @105 °C compared to other target gases. One of the key features of as-fabricatedWO3 MFs sensor is the lower detection limit of 125 ppb and operating temperature of 105 °C to NO2 with better reproducibility, signifying commercial prospective of the developed sensor materials. Finally, the gas sensing mechanism of WO3 MFs sensor has been proposed.

Yttrium oxide (Y2O3) has been widely used in metal-reinforced composites, microelectronics, waveguide lasers, and high-temperature protective coatings because of its good physical and photoelectric properties. However, few studies have been done on the nonlinear optical applications of Y2O3 as saturable absorbers (SAs) in fiber lasers so far. Here, a passively Q-switched near-infrared fiber laser using Y2O3 as a Q-switching device is demonstrated. The optical nonlinear properties of the Y2O3 SA prepared by the magnetron sputtering method were measured by the twin-detector measurement technique, and the modulation depth of the proposed Y2O3 SA was found to be 46.43%. The achieved Q-switched laser delivers an average output power of 26 mW at 1530 nm with a pulse duration of 592.7 ns. To the best of our knowledge, this is the first report on the optical nonlinearity of Y2O3 as a Q-switcher for the near-infrared fiber laser, which may deepen the understanding of the optical nonlinear properties of Y2O3 and make inroads into the potential market of optical modulation and optoelectronic devices.

In recent years, the diversity of transition metal dichalcogenides (TMDs) has made them occupy the essential status in the exploration of saturable absorbing materials. WTe2, also an important member of TMDs not only exhibits narrower band gap than MoS2 or WS2, but also has fast relaxation time, thus it has advantages in the realization of broadband absorption and ultrashort pulses. In this work, a WTe2 saturable absorber (SA) fabricated by magnetron sputtering technology features nonlinear absorption coefficient of −3.78 × 10−5 cm/W and modulation depth of 37.95%. After integrating this WTe2 SA into the ring cavity, a 164 fs mode-locked laser is achieved at 1557.71 nm. The laser remains stable about 8 h with an output power of 36.7 mW. The results show the favorable saturable absorption properties of WTe2, and further demonstrate the potential of WTe2 in the realization of ultrashort pulses, which indicates that WTe2 can be regarded as a possible candidate for future ultrafast lasers.

A p-GaN/i-MgO/n-ZnO nanorod array (NRA) heterojunction light-emitting diode has been fabricated. Its room-temperature electroluminescence spectra under different forward biases revealed a strong emission band across the whole visible region, which was blue-shifted when increasing the forward bias. The origin of this visible emission is considered to be related to oxygen vacancy (VO) defects in different valence states, where the blue emission (∼ 460 nm) comes from neutral oxygen vacancy (VOX ) defects and the green emission (∼ 520 nm) from singly charged oxygen vacancy (VO+ ) defects, while the yellow (∼ 580 nm) and red emission (∼ 670 nm) are attributed to doubly charge oxygen vacancy (VO++ ) defects. These VO defects in different states can convert into one another under different excitation conditions, resulting in the blue-shift of the emission peak as the forward voltage is increased.

During the application of semi-theoretical models to predict peak discharges for breached embankment dams, it is often encountered to be lack of necessary model parameters such as breach height. In order to solve this deficiency and improve the application of the semi-theoretical models for estimating the peak discharge, a mathematical relation is proposed to predict the breach height (Hb) using the water depth above breach bottom (Hw) based on a subset of a composite database (72 historical dam failures). The breach height relation has a high coefficient of determination (R2) when it is applied in the composite database. Using the prediction by the breach height relation as a substitute for the observation, these semi-theoretical models used here produce similar results in terms of both prediction accuracy and uncertainty. Moreover, the dispersion of the flood peak discharge predicted by forecasting models is weakened and the skewness is improved by adopting the breach height relation. Therefore, the application of semi-theoretical models to predict peak discharges can be improved obviously. So, it is found that the breach height using the proposed relation can be a satisfactory substitute when the observed value of Hb is unavailable in a dam failure. Besides, the prediction accuracy will decrease slightly with the increase of database, but the decrease is limited. It should be noted that the proposed breach height relation is only suitable for predicting the height of embankment dam breach in principle.

As an n-type oxide semiconductor, Ga2O3 shows great promise in solar-blind ultraviolet (UV) photodetectors due to its adequate band gap, high absorption coefficient, high thermal and chemical stability, high breakdown voltage, and high sensitivity to UV light. In order to investigate the photoresponse of the Ga2O3 photodetector with different crystallization status, we fabricated a series of β-Ga2O3 thin films on a sapphire substrate via pulsed laser deposition with different deposition temperatures from 250°C to 650°C. X-ray diffraction and scanning electron microscopy result showed crystallization enhancement due to the increasing of deposition temperature, and the crystallization procedure started at ∼ 450°C. Optical analysis indicated a blue shift present at the absorption edge (from 4.6 eV to 5.1 eV) with temperature increasing from 450°C to 650°C, showing modulation feasibility in the band gap due to temperature dependence. In addition, all samples showed high transmittance (over 90%) over the entire visible spectrum. Film detectors fabricated by these samples showed high photoresponse and high light/dark current ratio (ILight/IDark) on Ga2O3 deposited at 450°C. Transmission electron microscopy result for film deposited at 450°C showed that the top and bottom regions of films contained both amorphous and crystalline Ga2O3, while there was no crystallization in the middle area of the film, indicating that a combined amorphous-crystalline Ga2O3 film with adequate ratio of crystalline state can significantly enhance the photoresponse while restraining the dark current.

In this work, we investigate VSe2 for generating femtosecond and large energy mode-locked laser pulses for the first time. Two types of VSe2 based saturable absorbers (SAs), microfiber–VSe2 and VSe2/polyvinyl alcohol (PVA), are prepared, which exhibit strong nonlinear optical characteristics with a modulation depth (ΔT) of 22.5% and 1.849%, respectively. In contrast to other transition metal dichalcogenides (TMDCs), theoretical calculations show that VSe2 is a metallic TMDC SA. With the implementation of microfiber–VSe2, conventional soliton mode-locking Er-doped fiber (EDF) laser is demonstrated with an ultrashort pulse duration of 910 fs. Based on VSe2/PVA, a large energy EDF laser is established. The maximum single pulse energy is 25.57 nJ. This study suggests that VSe2 possesses application potential in ultrafast photonics and provides a valuable strategy for the development of TMDC based devices with desirable optoelectronic properties.

Thin-film transistors (TFTs) based on solution-derived metal oxides hold great potential in emerging low-cost large-area printed electronics. Despite recent impressive progress, these device performances are far behind those of their corresponding vacuum-based counterparts, impeding their future commercialization. In this work, we designed and created high-performance TFTs based on a nanometer-thick (down to 5 nm) crystalline In–Sm–O channel via aqueous solution processing, with a performance comparable to those of existing vacuum-processed metal oxides. The microstructural, chemical, optical, and electrical properties of the ultra-thin In–Sm–O samples as a function of Sm doping content (0–10%) were comprehensively investigated. The In–Sm–O TFTs (5% Sm) on SiO2/Si dielectrics demonstrated state-of-the-art performance, including a high mobility of 21.51 ± 1.33 cm2 V−1 s−1, subthreshold swing of 0.66 ± 0.06 V per decade, threshold voltage of 2.14 ± 0.44 V, on/off current ratio >108, and remarkable bias stress stability. The success of In–Sm–O was attributed to the high quality of the crystalline In2O3 matrix, the ideal nature of Sm dopant in suppressing oxygen vacancies, as well as the ultrathin and atomically smooth nature of the channel layer. Therefore, the aqueous solution-processed ultra-thin In–Sm–O channel is expected to enable the realization of future low-cost, large-area, and high-performance green electronics.

Large disturbance scenarios, such as pulse power load operation and load switching are commonly seen in the operation of dc microgrids. The mixed potential theory-based large-signal stability (LSS) analysis is a simple and practical method for investigating the LSS of dc microgrids. However, this method is characterized by conservatism, and produces conservative stability criterion results. When they are applied to the parameter designs of dc microgrids, they create excessive control parameter redundancies; when used for running status estimations, they may cause the system to be misjudged as unstable, and trigger unnecessary protective actions when the system runs into the conservative region. This paper presents a comprehensive analysis of the conservatism, revealing its main causes to be the idealization of the load converter's response characteristics, and the lack of refined models. It then proposes a novel, improved analysis method for transient response characteristics of the load converter. Experimental and simulation results using the improved method have validated it by showing that the conservatism of the traditional method had been eliminated, and the stability criterion obtained was more accurate.

The analytic multi-soliton solutions for nonlinear Schrodinger (NLS) equations are complex to obtain. Based on those solutions, interactions among multiple solitons show more abundant characteristics than two soliton interactions. With the Hirota method, bilinear forms and analytic soliton solutions of the coupled NLS equation are derived, and the influences of the dispersion parameter β(x) and constant parameters p1, p2 and p3 on soliton interactions are discussed in detail. The novel triple-S structures are presented via choosing suitable values. The phase, intensity and incidence angles of dark solitons are controlled with appropriate constant parameters. Besides, bound states of dark solitons are observed with different periods. In addition, the peculiar triple-triangle structures are presented when one sets β(x) as the hyperbolic tangent function. Results in this paper are useful for the generation and interaction of optical solitons in nonlinear optics and ultrafast optics.

We report a synchrotron Laue diffraction study on the microstructure evolution in zirconium (Zr) as it undergoes a pressure-driven structural phase transformation, using a recently developed real time scanning x-ray microscopy technique. Time resolved characterizations of microstructure under high pressure show that Zr exhibits a grain enlargement across the α-Zr to ω-Zr structural phase transition at room-temperature, with nucleation and growth of ω-Zr crystals observed from initially a nano-crystalline aggregate of α-Zr. The observed grain enlargement is unusual since the enlargement processes typically require substantially high temperature to overcome the activation barriers for forming and moving of grain boundaries. Possible mechanisms for the grain enlargement are discussed.

Transparent amorphous oxide semiconductor (TAOS) represented by a-InGaZnO (IGZO) has achieved their commercial success in the display industry due to its superior material properties (e.g. high mobility (>10 cm 2 V −1 s −1 ), good transparency and excellent uniformity). However, TAOSs with excellent electrical properties are all n-type due to the particular electronic structures of oxide materials. The absence of high performance p-type TAOS limits the device application such as complimentary circuit and is now the largest drawback for oxide electronics. Here, we propose a low-temperature solution method to fabricate p-type transparent amorphous nickel oxide (NiO). The influence of processing parameters such as annealing temperature, precursor concentration, source/drain electrode, and dielectric layer is systematically investigated to maximum the NiO device performance. The optimized NiO TFT exhibits outstanding p-channel behavior, including a high hole mobility of 6.0 cm 2 V −1 s −1 , remarkable on/off current modulation ratio of ∼10 7 , and good subthreshold swing of 0.13 V/decade. The high performance NiO device is attributed to the synergistic optimization of annealing temperature, channel thickness, source/drain electrodes, and dielectric materials. The properties of our p-type TAOS are comparable with that of traditional n-type TAOS.

Visible-light photocatalytic water splitting for hydrogen evolution has attracted tremendous attention in past decades, but it still suffers from low solar-hydrogen conversion efficiency. In this paper, two-dimensional (2D) CdS was synthesized by the hydrothermal method, and 2D CoP nanosheets were synthesized by successive hydrothermal, oxidation and phosphodation process. Then 2D-2D CdS–CoP photocatalysts were formed by ultrasonically dispersing the mixed solution of CdS and CoP, and their heterostructure was confirmed by transmission electron microscopy, X-ray photoelectron spectroscopy, fluorescence spectrometer and so on. CdS–CoP with 2% CoP loading amounts exhibits a maximum photocatalytic performance of 56.3 mmolg−1h−1 under visible light irradiation, which is 11.3 times as high as bare CdS. The enhanced photocatalytic performance of CdS–CoP should be due to the following two points: (1) high catalytic activity of CoP; (2) highly efficient separation and transfer of electron-hole pairs photogenerated in CdS due to the synthesized 2D-2D heterostructure.

High-pressure transitions are thought to modify hydrogen molecules to a molecular metallic solid and finally to an atomic metal1, which is predicted to have exotic physical properties and the topology of a two-component (electron and proton) superconducting superfluid condensate2,3. Therefore, understanding such transitions remains an important objective in condensed matter physics4,5. However, measurements of the crystal structure of solid hydrogen, which provides crucial information about the metallization of hydrogen under compression, are lacking for most high-pressure phases, owing to the considerable technical challenges involved in X-ray and neutron diffraction measurements under extreme conditions. Here we present a single-crystal X-ray diffraction study of solid hydrogen at pressures of up to 254 gigapascals that reveals the crystallographic nature of the transitions from phase I to phases III and IV. Under compression, hydrogen molecules remain in the hexagonal close-packed (hcp) crystal lattice structure, accompanied by a monotonic increase in anisotropy. In addition, the pressure-dependent decrease of the unit cell volume exhibits a slope change when entering phase IV, suggesting a second-order isostructural phase transition. Our results indicate that the precursor to the exotic two-component atomic hydrogen may consist of electronic transitions caused by a highly distorted hcp Brillouin zone and molecular-symmetry breaking. X-ray diffraction measurements of solid hydrogen provide crystallographic information for high-pressure phases of hydrogen and transitions between them, suggesting a series of isostructural transitions under compression before band closure and metallization.

Laue micro-diffraction has proven to be able to reveal material properties at the sub-grain scale for many polycrystalline materials and is now routinely available at several synchrotron facilities, providing an approach for nondestructive three-dimensional probing of the microstructures and mechanical states of materials. However, for in situ experiments, maintaining the positioning of the sample throughout the experiment, to achieve a good alignment of the characterized volumes, is a challenging issue. The aim of the present work is to address this problem by developing an approach based on digital image correlation of focused-beam Laue diffraction patterns. The method uses small changes in the diffraction signal as a focused X-ray beam is scanned over a surface region to allow corrections to be made for both sample lateral movement and rotation. The method is demonstrated using a tensile deformation experiment on an Al sample with 2.5 µm average grain size. The results demonstrate an accuracy of 0.5 µm for sample position registration and a precision in sample rotation of ∼0.01°. The proposed method is fast to implement and does not require the use of additional surface markers.

A small amount of cerium (below 1.0 wt%) addition to AZ91 alloy have been investigated on the hot tearing susceptibility (HTS) at a cooling rate of 1.5Ks−1. The HTS increased to a maximum value with a cerium addition of 0.6 wt% and then decreased to a stable status as cerium was gradually added. Due to high chemical activity, cerium into the melts can react with aluminum to form an Al11Ce3 intermetallic compound. X–ray diffraction results also confirmed the existence of Al11Ce3. The Al11Ce3 increased with the presence of the needle-like and block morphology. As cerium levels increased, the amount of Mg17Al12 decreased. The variations between Mg17Al12 and Al11Ce3 resulted in a similar normal distribution of the HTS in AZ91 alloy. The findings were further verified through the microstructure evolution and the surface morphology of fracture. Keywords: AZ91 alloy, Cerium addition, Hot tearing susceptibility, Microstructure evolution, Fracture mechanisms

Transition metal dichalcogenides have recently been considered the candidates for saturable absorption materials due to their advantages in both electronic and optoelectronic. Compared with MoS2 and WS2, MoTe2 exhibits smaller bandgap. As a result, MoTe2 owns inherent advantages in the near-infrared applications. In this paper, the MoTe2 saturable absorber (SA) were prepared by the magnetron sputtering deposition method. Owing to the enhanced light-materials interaction between MoTe2 and evanescent field from the microfiber, the modulation depth of the MoTe2 SA was up to 26.97%. By assembling the MoTe2 SA into the erbium-doped fiber laser, the mode-locked fiber laser at 1.5 μm was demonstrated. The pulse duration of 111.9 fs was proved to be the shortest in the fiber lasers based on transition metal dichalcogenides. Moreover, the mode-locked fiber laser maintains the long-term stability. Our results suggest that the proposed MoTe2 SA is promising for the ultrashort pulse generation and stable system operation.

Economical, efficient and earth-abundant oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts are highly required for Zn-air batteries, which is an attractive device for the next generation of energy storage. Herein, spinel-structured NiCo2O4 nanosheet with oxygen defects and ultrathin structure was developed as a bifunctional electrocatalyst for ORR and OER. The ultrathin thickness of NiCo2O4 nanosheets provided numerous active sites, and the oxygen vacancies improved the reactivity of the catalyst, thus leading to appropriate catalytic performance (an onset potential of 0.85 V for ORR and an onset overpotential of 340 mV for OER). Furthermore, the ultrathin NiCo2O4 nanosheets also showed superior activity for rechargeable Zn-air battery with the power density of 102.08 mW cm−2, which was comparable to the commercial Pt/C catalyst. The rational design in our study might be beneficial for the preparation of other high-performance bifunctional electrocatalysts.

At the occurrence of a permanent fault in a DC microgrid, apart from isolating the faulty section using a solid-state circuit breaker, the protection system should also have the fault position located so that repair crew can be sent to clear the fault and restore the isolated section. Available fault location methods are either influenced by network topology or need to add costly equipment. Located immediately next to the faulty line, the solid-state circuit breaker has the advantage of position required for injecting and detecting fault location signals, and it is isolated from the rest of the system by disconnector after fault interruption. Therefore, using the solid-state circuit breaker for fault location has a potential research value. However, it is rarely discussed in previous literatures. In this paper, an improved topology of the solid-state circuit breaker is proposed, which is able to inject signals into the isolated faulty line to determine fault position. By reusing components, the improved topology can achieve function expansion without much increasing the size and cost for fault protection, obtaining an accurate result uninfluenced by the network topology. Simulations and experiments are conducted in a 200 V/DC system to verify the effectiveness of the design.

Requirements of the transmission rate, transmission distance and transmission capacity of optical communication systems are becoming higher and higher, and studies on the higher-order effects such as third order dispersion are inevitable for the development of systems. In this paper, we study the influences of higher-order effects on the optical soliton transmission. The high-order nonlinear Schrodinger equation, which can be used to describe the optical soliton transmission in the fiber laser, is investigated. Analytic soliton solution for this equation is obtained. The comprehensive analysis of the solution is made. Through choosing different values of the high-order effects, we discuss their influences on optical soliton transmission speed, period and pulse width. Results can be used to guide the generation and transmission of optical solitons in experiments.

In order to better utilize and combine the advantages of poly(d,l-lactide) (PDLLA) matrix and natural polysaccharide chitin whiskers (CHWs), needle-like CHWs with chiral nematic liquid crystal characteristics and remarkable moduli were chosen to surface modify PDLLA film. By a vertical coating method, a stable and well-ordered CHWs coating was formed on the surface of the PDLLA film through a polydopamine (PDA) interlayer. The high stability of the well-ordered CHWs coating on the surface of the PDLLA film was confirmed by PBS soaking experiment in terms of the changes of weight and surface morphology of the film. The surface microstructure and composition of the resulting PDLLA-PDA-CHWs film were characterized by field emission scanning electron microscopy (FESEM), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS), and the thickness of the PDLLA, PDA and CHWs layers was determined using FESEM, too. Comparing with traditional PDLLA/CHWs film, prepared by solution blending with optimal content of 5 wt% CHWs, the hydrophilicity and mechanical properties of the PDLLA-PDA-CHWs film were significantly improved owing to the immobilization of a highly ordered CHWs coating. Furthermore, in vitro cell culture showed that the well-ordered CHWs coating had a more significant effect on promoting the adhesion, spreading, proliferation and osteogenic differentiation of MC3T3-E1 cells. All these results showed that the resulting PDLLA-PDA-CHWs film with well-ordered CHWs coating designed through simple and effective approach has promising application in bone repair material field.

Nonlinear control is widely used in optical communications, ultrafast optics and other fields. In this paper, nonlinear control based on the dark soliton is investigated in the dispersion management system. Dark soliton solutions for the third-order nonlinear Schrodinger equation are derived. Through changing the group velocity dispersion and nonlinear parameters, the propagation characteristics of dark solitons are discussed, and the influences of corresponding parameters on dark solitons are analyzed. Some nonlinear control methods based on specific parameters are suggested. Results are beneficial to the study of the dark soliton transmission.

All fiber Q-switched laser with its advantages of high energy, compact structure and high stability boosted the growing demand in many applications. We synthesized the regular iron oxide nanoparticles (IONP) in size of 12–15 nm via the chemical co-precipitation method. Using the IONP-PVA film as SA, high stable polarization-insensitive Er-doped Q-switched fiber laser was demonstrated. The prepared IONP SA exhibits saturation intensity of 13.44 MW/cm2. The shortest pulse duration was achieved to be 896 ns and the single pulse energy was up to 100 nJ with the maximum pump power of 500 mW. In particular, the polarization controller is unnecessary in our experiments, so the ring cavity can be compacted into a smaller size with 80 dB signal-to-noise ratio for the output pulse sequence. Such a compact, low cost and high stability Q-switched laser maybe expected to have the more extensive application prospect.

Investigations on soliton interactions in dispersion management systems are beneficial to improving the communication capacity. In this paper, the variable-coefficient fifth-order nonlinear Schrodinger equation, which can be used to describe the soliton interactions in dispersion management systems, is studied analytically. M-typed soliton interactions are presented based on the obtained soliton solutions. Influences of nonlinear effects on M-typed soliton interactions are analyzed. Results indicate that we can effectively control soliton interactions by means of nonlinear optimization of dispersion management systems.

Solitons are widely used in nonlinear optics, theoretical physics and other fields. In this paper, based on a spectral problem, the Dirac integrable equation is dealt with N-fold Darboux transformation, and analytic solutions for this equation are presented with the assistance of symbolic computation, and the propositions are provided for two different Darboux transformations. Two illustrative examples of the resulting solutions are displayed. Finally, their dynamic properties of those obtained solutions are discussed.

A series of hindered amine light stabilizer (HALS) with controlled molecular weight and narrow distribution was synthesized by reversible addition-fragmentation chain transfer(RAFT) polymerization,...

Zn1-xCdxO films with different Cd contents obtained by controlling the growth oxygen pressure (Op) were deposited on both c-sapphire (Al2O3) substrates and p-GaN substrates, by means of the pulsed laser deposition (PLD) method. Photoluminescence (PL) measurement revealed that the variation of Op influenced the amount of Cd doping into Zn1-xCdxO films deposited on Al2O3, leading tunable luminescence from the ultraviolet (UV) to blue emission extended to the green band. Then all the fabricated n-Zn1-xCdxO/p-GaN heterojunction possessed good ohmic contacts and exhibited typical rectifying characteristic of the diode. Indeed, the high luminescence from the ZnCdO layer could be attained by inserting a MgO insulator to the heterojunction interface. The fabrication of tunable n-Zn1-xCdxO/p-GaN heterojunction light-emitting diodes is available which was supported by the results of electroluminescence (EL) experiment.

While large-scale distributed generation (DG) grid connection requires its grid-connected converter to be able to boost the output voltage and connect it to the host grid, its priority is still to consume the power locally so as to increase the energy utilization rate. Using a common ac bus to transmit the distributed power to local load requires two separate converters, resulting in large size and multistage power conversion. Therefore, to lose the transformer and increase the compactness, a three-port nonagonal modular multilevel converter (MMC) is proposed in this paper, which consists of nine bridge arms connected from end to end. From the vertexes, three 3-phase ac ports protrude, connecting DG, ac grid, and local load together. By reusing power modules, with only nine bridge arms, the proposed nonagonal MMC realized three-port direct ac/ac power conversion in a single converter. Furthermore, the topology can operate without a transformer or high-voltage dc link, and under low frequency. It is then compared with other topologies to demonstrate its advantage in applications that require high compactness and flexibility. Finally, the proposed topology and its corresponding control are verified in RTlab to be effective for DG grid connection and local consumption.

Although hybrid circuit breaker (HCB) uses a combination of mechanical switch and insulated-gate bipolar transistors (IGBTs) to accommodate HVDC application, it still has a large number of series-connected IGBTs in its main breaker. Besides, in multiterminal HVDC system, three or more HCBs appear in cluster at one node, which worsens the HCBs’ disadvantage in volume. To simplify the breaker cluster’s topology structure and control system as well as increase the compactness, a multiport circuit breaker (MPCB) is proposed in this paper with its control procedure presented. By assembling the HCBs at one node, it can not only cut down the component count for fault interruption remarkably but also reduces the number of control signals. Apart from this, due to a more compact structure, the proposed circuit breaker avoided the use of a dc bus and, hence, dc bus fault which will result in disconnecting the node completely from the system. Hence, regardless of faults and their fault locations, it is always able to connect the remaining healthy ports together. Finally, the effectiveness of the proposed MPCB in different fault scenarios is verified by RTlab.

By employing localized surface plasmon resonance (LSPR), the near band edge (NBE) emission intensity of ZnO films were greatly varied, while defect emission remained almost the same. This photoluminescence (PL) intensity enhancement or reduction is tunable by changing the position of Ag nanoparticles (NPs) relative to the ZnO films. The remarkable variation of the NBE emission was investigated deeply. These experimental results reveal that the Ag NPs play a key role in tuning the PL performance of the semiconductor material, where LSPR occurs.

We demonstrated a mode-locked fiber laser based on a novel photonic device that combined optical microfiber coupler (OMC) and saturable absorption materials. The stable ultrafast laser was formed based on the interaction between the deposited Indium Antimonide (InSb) and the evanescent field on OMC. Different from optical microfiber (OM), OMC can directly output the mode-locked laser without additional beam splitting devices, which further improves the integrated characteristics of the fiber laser. The pulse duration of the output pulse is 405 fs at the central wavelength of 1560 nm. To the best of our knowledge, this is the first time that optical microfiber coupler based saturable absorber (OMC-SA) for mode-locked fiber laser is demonstrated.

With modern rapid and emerging development trend of Internet technology, great number of data are accumulated in the society, which leads to a larger data scale. With the target to discover the potential value of general data, it has been usually necessary to flexibly apply various data mining algorithms based on the actual situation and scenarios. The implementation of data mining algorithm is faced with great challenges in terms of execution efficiency, algorithm parallelization and platform usability. Different from horizontal text, multi-directional text and curved text, the surface text of surface object has some geometric features. In the detection phase, the text box label of surface text needs more vertex coordinates to express its spatial information, which makes it difficult to label large-scale samples. In the recognition stage, it is more difficult to recognize the surface text of the surface object than the regular text on the plane. At present, several universities ignore the importance to the construction of political education micro platform, and fail to develop a scientific micro platform according to the actual needs and interests of students. Based on this situation, this paper applies the data mining models and text recognition algorithm to study innovative smart political education platform.

As an excellent multifunctional single crystal, potassium dihydrogen phosphate (KDP) is a well-known, difficult-to-process material for its soft-brittle and deliquescent nature. The surface mechanical properties are critical to the machining process, however, the characteristics of deformation behavior for KDP crystals have not been well studied. In this work, the strain rate effect on hardness was investigated on the mechanically polished tripler plane of a KDP crystal relying on nanoindentation technology. By increasing the strain rate from 0.001 to 0.1 s−1, hardness increased from 1.67 to 2.07 GPa. Hence, the strain rate sensitivity was determined as 0.053, and the activation volume of dislocation nucleation was 169 Å3. Based on the constant load-holding method, creep deformation was studied at various holding depths at room temperature. Under the spherical tip, creep deformation could be greatly enhanced with increasing holding depth, which was mainly due to the enlarged holding strain. Under the self-similar Berkovich indenter, creep strain could be reduced at a deeper location. Such an indentation size effect on creep deformation was firstly reported for KDP crystals. The strain rate sensitivity of the steady-state creep flow was estimated, and the creep mechanism was qualitatively discussed.

Digital analysis of the current situation of network ideological education propaganda in colleges based on remote data modeling is conducted in this manuscript. The introduction of the neural network aims to quickly and effectively remove auxiliary variables that are not sensitive to the target variable, improve the model training effect, and avoid the long training time caused by the selection of too many variables and the risk of overfitting. Data packets may need to be forwarded by the multiple intermediate nodes in the communication network to reach the destination node. Based on the innovations on the proposed model, it has been applied into the education applications. The experiment has provided efficient results for further analysis.

Janus transition metal dichalcogenides with unique physical properties have recently attracted increasing research interest for their energy and catalytic applications. In this paper, we investigate the lithiation behavior of a square phase Janus MoSSe monolayer (1S-MoSSe) using first-principles calculations. Computational results show that a single Li atom energetically prefers to adsorb on the central site of the octagonal ring (O site) and on the S-layer side of 1S-MoSSe. The predicted energy barriers for Li diffusion are surface dependent and in the range of 0.33 to 0.51 eV, indicating the acceptable Li migration kinetics on 1S-MoSSe in comparison with other 2D TMD materials. Further thermodynamic analysis demonstrates that Li adsorption on 1S-MoSSe is energetically stable up to a Li concentration of x = 1.0, above which the lithiation process becomes unstable with a negative charging potential. Phonon calculations also confirm that Li adsorption (0.25 ≤ x ≤ 0.75) results in the lattice distortion of 1S-MoSSe in order to suppress the structural instability of the lithiated monolayer 1S-LixMoSSe with imaginary phonon frequencies. The less symmetric nature of 1S-MoSSe is believed to destabilize Li adsorption at much smaller x than 1H-MoSSe does, regardless of the higher dipole moment of 1S-MoSSe. This computational study provides a fundamental understanding of the electrochemical performance of 1S-MoSSe, as well as useful insight into the material design of Janus TMD anodes for Li-ion batteries.

In order to study the relationship between the degree of deacetylation of chitin whiskers (CHWs) and their enzymatic degradation properties, in this paper, CHWs were first deacetylated to different degrees by alkali treatment, and the CHWs with the degrees of deacetylation of 17.84, 67.76, and 82.54% was obtained, respectively. Moreover, the partially deacetylated CHWs still maintained good crystallinity and nanoneedle-like morphology. Next, the in vitro degradation behavior of CHWs with different degrees of deacetylation was further studied under the single or synergistic action of lysozyme and lipase (37 °C, pH = 7.4). The results showed that the morphology change of CHWs was more obvious as the degree of deacetylation increased. The mass loss, the crystallinity index at the (110) crystal plane, and the concentration of reducing sugar of the CHWs also increased with the degree of deacetylation. Moreover, the synergistic effect of the two enzymes was more conducive to the degradation process of CHWs than single lysozyme or lipase. The difference in the rate of enzymatic degradation provides an idea for the regulation of the degradation rate of the CHWs.